<!doctype html>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script>
promise_test(async t => {
  let start_length = navigation.entries().length;
  let start_index = navigation.currentEntry.index;
  // Wait for after the load event so that the navigation doesn't get converted
  // into a replace navigation.
  await new Promise(resolve => window.onload = () => t.step_timeout(resolve, 0));
  await navigation.navigate("#foo").finished;
  assert_equals(navigation.entries().length, start_length+1);
  await navigation.back().finished;
  assert_equals(navigation.currentEntry.index, start_index);

  // Traverse forward then immediately do a same-document push. This will
  // truncate the back forward list, and by the time the traverse commits, the
  // destination key will no longer be present in navigation.entries(). The
  // traverse should abort. Because the traverse aborts before the navigate
  // event fires, the navigateerror event should not fire.
  navigation.onnavigateerror = t.unreached_func("navigateerror should not fire");
  let forward_value = navigation.forward();
  await navigation.navigate("#clobber").finished;
  assert_equals(navigation.currentEntry.index, start_index+1);
  await promise_rejects_dom(t, "AbortError", forward_value.committed);
  await promise_rejects_dom(t, "AbortError", forward_value.finished);

  // This leaves navigation.entries() in a consistent state where traversing
  // back and forward still works.
  await navigation.back().finished;
  assert_equals(navigation.currentEntry.index, start_index);
  await navigation.forward().finished;
  assert_equals(navigation.currentEntry.index, start_index+1);
}, "If forward pruning clobbers the target of a traverse, abort");
</script>
